This invention relates to the manufacturing and assembly of movable sockets, for example, ball-joints as used in automotive steering and suspension systems, and more particularly, to a method and device for performing dual operations of closing one end of a movable socket without spinning, swaging, or welding, by means of an expanding cover-plate, and for producing a centrally located orifice of predetermined size in the cover-plate. While the invention is described in detail with respect to automotive applications, those skilled in the art will recognize the broader applicability of the invention.
Conventional ball-joints, and other movable sockets are used, for example, in automotive steering and suspension applications. The sockets comprise a housing having a circular cylindrical internal surface, a ball stud with a ball head contained in the housing, and a synthetic resin, heat treated steel, or sintered alloy bearing member supporting the ball head within the housing. These components are installed into the housing through a posterior opening, with the ball stud extending outward through an axially disposed anterior opening of a smaller diameter than the ball head. Traditionally, the posterior opening is closed by means of a cover-plate, which is spun or swaged in place, as seen in FIGS. 1A-1D. Alternatively, the cover-plate may be welded into place.
Cover-plate elements are traditionally formed from a stamping process, whereby individual components having desired dimensions are stamped from metal sheets. Either during the stamping process or in a subsequent manufacturing step, a raised boss may be drawn or stamped into the cover-plate, and a centrally located hole of predetermined dimensions punched therein to receive a self-tapping or threaded grease fitting.
Once secured in place, the cover-plate presses on the bearing member either directly or indirectly through a resilient rubber intermediate component and a pressure plate.
Bearing components within the housing, against which the ball head or moveable component is articulated, perform best when the housing material is fully hardened, as it is better able to withstand the stresses and frictional wear associated with movement of the bearing components. Accordingly, the use of hardened materials greatly extends the useful life of the bearing components and the housing. However, hardened material surfaces greatly hinder traditional spinning, swaging, or welding operations required to enclose the housing.
As described in co-pending U.S. patent application Ser. No. 09/167,917 filed on Oct. 7, 1998 now U.S. Pat. No. 6,202,280, (herein incorporated by reference) a method and device for expanding a conical or convex cover-plate within the posterior opening may be employed to secure and enclose the socket components within the socket housing, allowing for closure of a fully hardened housing without the need for traditional spinning, swaging, or welding operations.
Alternatively, as is described in U.S. Pat. No. 6,125,541 to Parker, herein incorporated by reference, a two-stage ram having first and second contact surfaces may be utilized to first expand a conical or convex wear-indicator style cover-plate within the posterior opening of a housing, and then to further deform the cover-plate to a predetermined final position relative to the internal components of the socket to provide a predetermined wear indicator distance. Once assembled, movable sockets may be utilized as load carrying members in numerous mechanical systems, including automotive vehicle suspension and steering systems. Obviously, movable sockets or ball-joints employed in these applications are subjected to various operating conditions, and may be required to carry substantial loads. When wear develops, the performance of the movable socket or ball-joint degrades and, in the case of automotive applications, may result in erratic steering or excessive looseness and play in the vehicle suspension system.
Accordingly, it is highly advantageous to develop a ram device capable of both expanding a conical or convex general-purpose cover-plate within a socket housing to enclose the housing without the need for specialized spinning, swaging, or welding operations. It is further highly advantageous to incorporate into the ram device, elements for establishing a desired cover-plate contour and a central orifice in the general-purpose cover-place of a predetermined size for the installation of a self-tapping grease fitting in a single machining operation.
Among the several objects and advantages of the present invention are:
The provision of an apparatus for expanding a conical or convex cover-plate to secure socket components within a socket housing and for establishing a central orifice in the cover-place of a predetermined size for the installation of a self-tapping grease fitting in a two-stage continuous operation;
The provision of the aforementioned apparatus wherein a contact surface expands the cover-plate within the housing, and an axially aligned pivot punch independently establishes a central orifice in the cover-place of a predetermined size for the installation of a self-tapping grease fitting;
The provision of the aforementioned apparatus wherein the contact surface is configured to expand the cover-plate within the housing and to produce a centrally located raised section or boss of predetermined height for clearance of internal socket components;
The provision of the aforementioned apparatus wherein the contact surface and the pivot punch are concentrically mounted within a ram housing;
The provision of the aforementioned apparatus wherein the pivot punch prevents the cover-plate from collapsing into a downward concave configuration during expansion;
The provision of the aforementioned apparatus wherein the pivot punch holds the cover-plate against the contact surface, forcing the cover-plate to conform to the surface configuration of the contact surface;
The provision of the aforementioned apparatus wherein the profile of the contact surface may be altered to numerous configurations ranging from flat to that which produces a centrally located raised section or boss in the cover-plate;
The provision of the aforementioned apparatus wherein the pivot punch includes an axial bore facilitating the injection of lubricant into the socket assembly in a single machining operation with the socket closing and orifice formation.
The provision of a method for use of the aforementioned apparatus wherein the cover-plate expansion operation and the cover-plate orifice establishing operation are integrated into a two-stage continuous pressing operation; The provision of the aforementioned method of use wherein the cover-plate expansion operation is a first stage operation, and the cover-plate orifice establishing operation is a second stage or sequential operation; and
The provision of the aforementioned apparatus and method which simplifies the assembly and manufacture of movable sockets to close tolerances while providing minimal unit-to-unit variations.
Briefly stated, the present invention features an assembly technique for enclosing an open end of a movable socket comprised of fully hardened materials with an expanding cover-plate and for establishing a central orifice in the cover-place of a predetermined size for the installation of a self-tapping grease fitting. During assembly, various internal components of the movable socket, including a pressure plate, are installed within a housing through a posterior opening and a conical or convex cover-plate is positioned over the components within the posterior opening. A ram of the present invention having a contact surface is brought into engagement with the cover-plate. Pressure exerted by the ram is transferred to the cover-plate through the contact surface, expanding the cover-plate. As the pressure is exerted by the ram, a coaxially located pivot punch is extended through a central bore in the contact surface, and engages an inner edge of the cover-plate. Continued engagement between the contact surface, pivot punch, and the cover-plate results in the cover-plate conforming to the contour of the contact surface during the expansion process, enclosing the internal components within the socket housing. As the cover-plate expands, the engagement between the pivot punch and the inner edge of the cover-plate established a central orifice in the cover-plate of a predetermined size. Additionally, lubricants may be injected into the now closed socket through a central bore in the pivot punch.
The foregoing and other objects, features, and advantages of the invention as well as presently preferred embodiments thereof will become more apparent from the reading of the following description in connection with the accompanying drawings.